Given the harmful consequences of global warming effects, there exists a current drive to develop carbon capture systems with the goal of reducing carbon dioxide (CO2) levels discharged into the atmosphere and the environment. A typical carbon dioxide capture/hydration method involves the absorption of generated CO2 into basic, aqueous solutions. The role of the base in the medium may be fulfilled by an organic amine base such as monoethanolamine (MEA). While efficient, this typical methodology contains inherently strong drawbacks that raise concern about its implementation in large scale productions. For instance, the basic solutions are expensive to use and regenerate, as the regeneration process often employs temperatures exceeding 100° C. to liberate the captured CO2. Additionally, the cost to a coal powered plant for driving this energy intensive process is about 20-30% of the total energy produced by the plant, which may translate into a substantial increase in energy cost for consumers.
A known, alternate approach to the use of basic solutions for CO2 capture is the employment of carbonate solutions. Unfortunately, the rate of absorption of CO2 by carbonate-based solution is orders of magnitude slower than their amine-based counterparts. However, the rate of CO2 absorption may be enhanced via the addition of catalysts such as carbonic anhydrase (CA). Carbonic anhydrase is an enzyme that catalyzes the conversion of CO2 into bicarbonate according to equation (1) below. The turnover rate for CA is about 106 mol−1 s−1, making it one of the fastest enzymes in biological systems.

Although the use of CA may result in an overall enhancement and improvement of the carbon capture process, the enzyme's function is greatly limited by the pH of the solution as well as the temperature of the environment. These are two issues that typically plague any process utilizing an enzyme as its main functional unit. Moreover, enzymes, in general, are also sensitive to highly saline or alkaline environments, where both denaturation and peptide hydrolysis may occur. For these reasons other viable systems are often sought for replacement.
Accordingly, zinc (II) cyclen (reproduced below), another active small molecule catalyst, is currently utilized in carbon capture systems, as it is capable of carrying out the hydration of CO2 in a manner similar to CA.
This small molecule mimic possesses characteristics that make it a superior candidate for use in industrial applications, such as its ability to withstand temperatures up to 120° C. and still retail catalytic activity upon cooling of the solution. However, while Zn2+ cyclen catalyzes the hydration of CO2 with a rate constant of about 103 mol−1 s−1, its catalytic profile still does not equal that of CA.